Product Reviews

November 08, 2006
November/December 2006
A version of this article appears in the November/December 2006 issue of Home Energy Magazine.
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GridPoint Connect

Fronius USA offers GridPoint Connect, a line of plug-and-play appliances for grid-connected PV installations that includes everything but the PV panels. The unitary devices package all of the balance-of-system components (including the inverter, charge controller, electronics, and recyclable gel batteries) in a single cabinet about the size of a small refrigerator--24 inches wide x 26 inches deep x 52 inches high—which clocks in at a hefty 900 lb. The system provides a clean, easy-to-install, professional-looking approach that appeals to mainstream users who would be intimidated by banks of wired-together components.

The GridPoint device connects the main circuit breaker panel to a renewable energy generator such as PV panels, which supplies local power and keeps the GridPoints batteries topped off. Excess power is sold into the utility grid. If the grid suffers a blackout, brownout, surge, or other distribution problem, the GridPoint system automatically isolates secure loads and continues to power them from the renewable energy generating source and/or the batteries. Depending on the selected options, the battery pack supplies 10-50 kWh of autonomy.

GridPoint is poised to take advantage of the nationwide implementation of dynamic pricing, which is mandated by federal law to be offered to all consumers by February 2007. It makes sense to dip into the battery backup during times of peak demand to cover any energy generation deficit of the renewable system, and then recharge the GridPoints batteries later, using grid power when theres more of it available and its cheaper.

Another aspect of the system that is enticing to hands-off homeowners is its monitoring capability. The computerized device communicates with GridPoint, keeping tabs on the systems operating efficiency and issuing maintenance alerts as needed. The GridPoint Central personal Web portal also provides a layer of automated, user-definable, energy management tools. For example, the (electric) water heater or air conditioner can be turned off while nobodys home, or the clothes washer and dryer can be set to run only during off-peak hours.

Most important, perhaps, is the user-educational data mined from the monitoring system. The system tracks such things as how much renewable energy the system has produced versus how much the occupants have used, and it shows how occupants use patterns affect the utility bill. And by providing environmental data--such as the amount of CO2 emissions that have been prevented by using renewable energy--it gives occupants a better understanding of how their energy use affects the world outside the house.

Fronius USA LLC—GridPoint, Incorporated, is located in Washington, D.C.
Tel: (202)903-2100;
Web site:

Solar-Heated Air from Environmental Solar Systems
Environmental Solar Systems offers the SunMate hot air solar-thermal collector for residential space-heating applications. It works by pulling cool air from inside the house, warming it with solar energy, and then recirculating it into the house. A thermostatically controlled, 12V DC, brushless fan (drawing 7 watts to move 100 CFM) kicks on when the absorber plate in the panel reaches 110°F, and turns off when it gets down to 90°F. One panel heats up to 300 ft2; and multiple panels can be installed in parallel. Alternatively, the SunMate can be configured as a solar-heated fresh-air intake.

The sleek, dark, modern-looking panels are made with stainless steel and aluminum components and frame, double-sealed solar glazing, and polyisocyanurate insulation. They measure 4 inches x 35 inches x 77 inches, weigh 110 lb, and are designed to be mounted vertically on the south-facing outside wall of a building. The installation kit comes with mounting hardware and includes an AC transformer--energy conscious do-it-yourselfers will probably want to use a small PV panel to power the fan.

Environmental Solar Systems is in Methuen, Massachusetts.
Tel: (978)975-1190; Web site:

Solar-Heated Water from Stiebel-Eltron

The copper absorber in the low-profile SOL 25 collector panel from Stiebal-Eltron has a net surface area of nearly 27 ft2. A light-selective coating helps produce a maximum output of 6,826 BTU per panel—2,000 watts of heating—with a maximum heat transfer fluid temperature of 410ºF. The assembly is housed in an aluminum frame with high-light-transmission tempered glazing. Copper piping is used throughout for the polypropylene glycol heat transfer solution. Exterior dimensions are approximately 88 inches x 48 inches x 3 inches; the dry panel weighs about 106 lb.

The SBB Plus glass-lined, heavy steel storage tanks come in two sizes--the model 300 is 80 gallons, and the model 400 is 108 gallons. Both sizes have dual, coil-type heat exchangers--one for the solar system, and one for a boiler. Three inches of foam insulation reduce 24-hour standby losses to 1.9 kW and 2.2 kWh, respectively. Installation hardware and accessories are available through the manufacturer.

Stiebel-Eltron, Incorporated, is located in West Hatfield, Massachusetts. Tel: (413)247-3380; Web site: 

Mark Piepkorn is the lead products researcher for Building Green, Incorporated. He is coeditor of the GreenSpec directory, and the book Green Building Products. He is an associate editor for the monthly journal Environmental Building News.
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